1. Field of the Invention
This invention relates to a method for judging errors in applying a liquid sample during a biochemical analysis, with which a specific constituent in the liquid sample is analyzed chemically. This invention particularly relates to a method for judging errors in applying a liquid sample during a biochemical analysis wherein a droplet of liquid sample is applied to an analysis medium, such as a chemical analysis slide or test film, containing a reagent which reacts with the liquid sample, and the optical density, which depends on how much of a reaction product was formed by the reaction between the liquid sample and the reagent in the analysis medium, is determined.
2. Description of the Prior Art
Qualitative or quantitative analyses of specific chemical constituents in liquid samples are conducted for various industrial purposes. Particularly, it is very important in biochemical and clinical fields to be able to quantitatively analyze certain chemical or physical constituents in body fluids such as blood or urine.
Recently, as disclosed in, for example, U.S. Pat. Nos. 3,992,158 and 4,292,272, dry type chemical analysis slides were developed for use in systems designed for performing quantitative analyses, with which systems the concentration of specific chemical constituents or specific physical constituents contained in a droplet of liquid sample, which is applied to the chemical analysis slide, is determined. It is possible to analyze a liquid sample more simply and more quickly with methods in which chemical analysis slides are used than with methods in which conventional wet type analyses are carried out. Therefore, it is more desirable to use chemical analysis slides, particularly in medical organizations, research laboratories, or the like, where many samples must be analyzed, than to carry out conventional wet type analyses.
In order for a chemical analysis slide to be used in the determination of the concentration of a specific constituent contained in a liquid sample, a measured amount of the liquid sample is put on the chemical analysis slide and is kept at a predetermined temperature (i.e. incubated) for a predetermined time in an incubator, which causes a color reaction. The chemical analysis slide is then exposed to light having a wavelength which is selected in advance. The selection of the wavelength depends on the constituents of the liquid sample and the constituents of a reagent contained in the reagent layer in the chemical analysis slide. Light is thus irradiated to a reaction product which forms on the chemical analysis slide, and the amount of light reflected by the reaction product is measured. The optical density of the chemical analysis slide is then found from the measured amount of reflected light.
Also, as a means with which liquid samples can be automatically and sequentially analyzed, a novel apparatus is proposed in, for example, U.S. Pat. No. 3,526,480. In the proposed apparatus, a long tape-like test film containing a reagent is used instead of the aforesaid chemical analysis slides, and the application, incubation and measurement of samples are carried out sequentially on adjacent portions of the test film.
In general, in the biochemical analysis apparatuses utilizing the analysis medium, such as a chemical analysis slide or test film, a sample application pipette is used to apply a droplet of liquid sample to the analysis medium. The sample application pipette is immersed in a liquid sample contained in a vessel, and takes up a small amount of the liquid sample by air suction. Thereafter, the sample application pipette moves to a position above an analysis medium and applies a predetermined amount of the liquid sample to the analysis medium.
In cases errors occur in the operation of the sample application pipette, or in cases the amount of the liquid sample contained in the vessel becomes insufficient, the problem occurs in that no liquid sample is applied to an analysis medium, or only an insufficient amount of the liquid sample is applied to an analysis medium.
In the conventional biochemical analysis apparatuses utilizing the analysis medium, such as a chemical analysis slide or test film, no judgment has heretofore been made as to whether or not errors occurred in applying a liquid sample to an analysis medium. Therefore, even when a value obtained from a quantitative analysis of a specific constituent was extraordinarily small, it could not heretofore been judged whether the value obtained is correct or is small because of errors in applying the liquid sample.